Research and Correction on Cone Angle Effect of CBCT

Abstract:

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The cone angle effect of CBCT system and affecting reconstructing slice are discussed. The CC-FDK algorithm is introduced. The redundancy data is not disposed accurately in FDK algorithm. The thesis puts forward a weighting projection method based on cone angle and distance to center plane. The method compensates the information of projection unused in FDK algorithm. The simulation model is scanned and reconstructed. The result indicates that this method can extend the cone angle of scanning.

Abstract: Using the Least Mean Square (LMS) algorithm, this paper simulates two smart antenna models under the same signal environment. By analyzing and comparing 8-antenna elements linear array and 2*4- antenna elements rectangular array, this paper proposes the way to design the heterotypic antenna model. This antenna array can help system to gain similar performance of signal to interference plus noise radio(SINR) with reduced size of the antenna. The paper realizes the simulation of two models with the LMS algorithm. The antenna pattern and the curve about convergence of error have been given. It also analyzes the influence of the step length factor on LMS algorithm performance, and finds out the reasonable step to ensure fast algorithm convergence and to suppress interference effectively.

Abstract: In order to improve the real-time character of missile radiator tracking and solve the predicting tracking problem when missile radiator shortly shelter or missing, it introduces moving target predicting and tracking technology. According to the predicting and tracking method, it proposes three predicting and tracking overall schemes of missile radiator based on Kalman filtering and improved Mean-Shift algorithm. Also it compares the real-time character of three kinds of schemes. According to the trajectory character of missile radiator, it constructs Kalman filter. The experiment results indicate that by using Kalman filtering technology, there are improvements in real-time character and shortly shelter or missing problem can be solved well. It plays a certain compensation function to the whole system.

Abstract: In addition to the conventional obstacle avoidance capabilities, the Unmanned Ground Vehicles (UGVs) used in military environments should be capable of avoiding certain areas which could inflict damage to the UGVs or result in the failure of the mission. The threat area could be minefields or an area vulnerable to enemy fire or detection. In this paper we have proposed and implemented an algorithm for ‘Threat Area Avoidance (TAA)’. Our algorithm was incorporated in two of the obstacle avoidance methods, Vector Polar Histogram (VPH) and the Enhanced VPH. The performance of our algorithm was evaluated in terms of distance overhead, navigation time, computational time and UGV Orientation Angle Variation Index. Through simulations, we observed that the proposed algorithm avoids a potential threat area (even though it is free of any obstacles) and takes a safe path while navigating between the start and goal points, with minimum overhead in computation.

Abstract: A new algorithms for parameters of an image irregular boundary circle parameters is presented, which is based on “Curve-Approximate Method” .For a set of an image circle boundary points by image pre-processing, firstly this paper introduces a substitute variant curve approximate reputably while picking out the irregular boundary points in all points, until to fit the terminate condition. Finally, it succeeds to get the optimal estimation of parameters of a circle. Example show that the algorithms runs more quickly and automatically than traditional generalized hough transform, and a good result is obtained if the irregular boundary points is small proportion in all points of a circle.

Abstract: The right panel drawing direction is an important prerequisite for generating qualified parts, an important step before the panel forming simulation is to determine the reasonable direction of the drawing. Manually adjust parts in order to overcome rely on experience, the drawbacks to the drawing direction, the direction of the drawing punch and forming the contact area of the sheet as the goal of automatic determination algorithm. Objective function of the direction of the drawing for the variable contact area in the drawing direction of the feasible region, the use of heritage algorithms to optimize the objective function of the contact area and, ultimately feasible within the contact area corresponding to the drawing direction, that is the best drawing direction. The measured results show that the direction of the drawing based on genetic algorithm, the automatic algorithm can fast and accurate to obtain the optimal direction of drawing.